Plug and Play in Home and Building Automation Systems by seg11239

VIEWS: 19 PAGES: 10

									                                   Plug and Play
                                   in Distributed Home and
                                   Building Automation Systems:
                                   An Introduction



                                                       Georg Neugschwandtner
                                    A-Lab, Automation Systems Group, TU Vienna
                                                    www.auto.tuwien.ac.at/a-lab




This presentation discusses the goal of reducing the setup time of home and
building automation systems. It offers a look into what this task involves, pointing
out requirements and challenges. A special focus is placed on how bindings
between communication endpoints can be established, including an overview of
respective KNX and LON mechanisms.


This presentation is intended as a tutorial to provide a better understanding of the
goal of “Plug and Play” – independent of particular implementations –, outline
what is being addressed today and what remains to be done.
              Plug and play?

                      A home or building automation system consists of
                      various geographically dispersed parts
                        • Sensors, actuators, user interfaces; controllers,
                          gateways

                      Goal: Take a hardware component „out of the box“,
                      add it to the system and make use of it without
                      further configuration
                        • More realistically: Reduce setup time as far as
                          possible

                      Reduced setup time               reduced overall cost
                        • Also reduces risk of configuration errors

Georg Neugschwandtner                     KNX Scientific Conference 2007, Duisburg     Page No. 2
Automation Systems Group, TU Wien                                                    November 07




              Course of talk

                      Functions of home/building automation systems
                        • What we want the system to achieve

                      Breakdown of configuration tasks
                        • What it takes for these functions to be achieved

                      Key aspect: Bindings between communication
                      endpoints
                        • Brief look on different ways to establish them
                          in KNX and LonWorks ISI
                        • Some thoughts about describing endpoint semantics

                      Outlook


Georg Neugschwandtner                     KNX Scientific Conference 2007, Duisburg     Page No. 3
Automation Systems Group, TU Wien                                                    November 07
              System scope & functions

                      Building automation: functional buildings
                        •     Energy efficiency, optimised management and
                              detailed accounting (usage reports)
                      Home automation: residential settings
                        •     Energy efficiency a growing concern,
                              although still largely comfort and peace-of-mind

                      Core domain: HVAC, lighting/shading
                        •     Measurement and control
                        •     Monitoring, diagnostics, optimization of the control process

                        •     Complex targets: Thermal comfort, lighting suited to current mood/task, ...
                                Continuous manual intervention part of routine system operation

                      Increasingly also: security, safety, A/V control /
                      consumer electronics, household appliances
                        •     High-level control information exchange between stand-alone systems
                              vs. “deep” integration



Georg Neugschwandtner                              KNX Scientific Conference 2007, Duisburg                       Page No. 4
Automation Systems Group, TU Wien                                                                               November 07




              Implementation dimensions

                      “Smart”, microcontroller enabled system components allow
                      efficient transfer of complex information
                         Embedded network, distributed system
                      How shall the system function(s) be implemented?
                       • Design choices have to be aligned for all devices

                                                  Dynamic performance parameters                   Interchangeable

                                                    (Partial) application functions                Interoperable
               Application
                    profile                             Data type semantics

                                                     (Process) data type syntax                    Interworkable

      Communication                          Communication interface (application layer)           Interconnectable
              stack
                                        Medium Access Control procedures / physical aspects        Coexistent

                                                     Levels of (runtime) functional compatibility (IEC 61804-1)

Georg Neugschwandtner                              KNX Scientific Conference 2007, Duisburg                       Page No. 5
Automation Systems Group, TU Wien                                                                               November 07
              Making choices

                      When setting up an automation system, no one starts
                      from scratch.
                        • Use available system technologies
                        • Developers have already thought about the same problem
                          and made appropriate choices
                        • Medium access algorithms, protocol services, data
                          encodings, standard function blocks

                      But every project is different!
                                                                                  Can be determined by
                        • Network topology
                                                                                    smart algorithms
                        • Application parameters
                          (time off delay, PI parameters)
                                                                                        Requirements, must be
                        • How many lights, which switches?                               provided by humans


Georg Neugschwandtner                        KNX Scientific Conference 2007, Duisburg                        Page No. 6
Automation Systems Group, TU Wien                                                                          November 07




              Making (project-specific) choices easier

                      Designing the system towards reducing setup time
                        • Statically predefine as much as reasonably possible
                        • Allow automatic detection of project specific choices
                        • Simplify required manual configuration
                      Decisions concern communication stack as well as
                      application profile/model
                        • Support for multiple segments / media, function block design, …
                      Simplicity vs. flexibility
                        • Fewer choices        quicker and easier setup
                        • Required flexibility depends on user’s demands (and budget)
                        • Different systems for different types of projects
                      Smart P&P approaches allow a better trade-off
                        • Cleverly manage (hide) the complexity that comes with flexibility
                        • System attractive for wider range of project types

Georg Neugschwandtner                        KNX Scientific Conference 2007, Duisburg                        Page No. 7
Automation Systems Group, TU Wien                                                                          November 07
              Hiding complexity

                      Automatic configuration
                        • Simplest case: Reasonable defaults (override only when required)
                        • Can only choose from possibilities that it was designed to deal with
                      Simplify required manual configuration
                        • Support manual choices to only require essential input
                        • Needs to take into account the organisation of the setup process,
                          actors’ competence levels and allowable training effort
                        • Includes usability concerns (UI design, ...)
                      Both depend on smart system model design
                        • Powerful concepts that can nevertheless be grasped quickly and
                          handled efficiently
                      Impact on resource requirements?




Georg Neugschwandtner                            KNX Scientific Conference 2007, Duisburg          Page No. 8
Automation Systems Group, TU Wien                                                                November 07




              Project tasks

                                    Specify overall requirements on building services

            Apply specialised domain knowledge for dimensioning plants and systems
                      (select actuators and sensors, design control loops)

             Apply high-level domain knowledge to define high-level control integration

                    Break down the functionality and decide on the realisation (devices)

                                         Physically install and connect devices

                Commission programmable devices: program, configure, parameterise

                                                              Test

Georg Neugschwandtner                            KNX Scientific Conference 2007, Duisburg          Page No. 9
Automation Systems Group, TU Wien                                                                November 07
              Task assignment: buildings vs. homes

              Building automation                                        Home automation

                      Tasks tend to be assigned to                            Less specialisation
                      different persons, strongly based on
                      division of labour                                      Self-installation (esp. white goods,
                                                                              brown goods) and management by
                       • Design the software configuration                    the end-user
                       • Install the devices
                       • Actually configure the devices                       No separate automation trade
                      Continued in operation phase                              •   Integrated automation solutions
                                                                                    partially provided by individual
                        •     Tenants may only activate scenarios                   trades and white/brown goods
                              or fine-adjust temperature set points,                manufacturers
                              rather than set up or modify them

                      Automation is a separate trade                          Configuration effort has a large
                        •     But HVAC and electrical trades no               share in system cost
                              longer provide stand-alone systems                •   Application templates required
                                                                                •   Should still be flexible enough and
                      Configuration effort offset by large                          leave room for custom extensions
                      number of identical sub-applications
                        •     Useful: simplify download of
                              predefined setup (also with regard
                              to maintenance)



Georg Neugschwandtner                                  KNX Scientific Conference 2007, Duisburg                            Page No. 10
Automation Systems Group, TU Wien                                                                                         November 07




              Appropriate solutions

                      With this background, the system designer can weigh
                      requirements …
                        • Which features shall the application have in the end?
                        • Where do I need flexibility? Where do I go for simplicity?
                      … and decide which particular task to support
                        • Cater to competence level, organisational background, …


                      For example, …
                        • No configuration tool should be required for connecting
                          household appliances
                        • For deployment in functional buildings, mechanisms need to
                          scale to large numbers of devices



Georg Neugschwandtner                                  KNX Scientific Conference 2007, Duisburg                            Page No. 11
Automation Systems Group, TU Wien                                                                                         November 07
              Supporting the commissioning step

                      Functions and their realisation have already been decided on
                      Factory-new devices need to be told their purpose
                        •     Establish bindings between communication endpoints of device applications
                      Ideally, they should be able to find out by themselves
                      Unless they match more than one place in the overall application
                        •     Manual intervention required to resolve ambiguities


                      Entire application and device mapping predefined with
                      configuration tool?
                        •     Ambiguities at device level
                        •     Typically in larger projects
                      Device mapping only defined implicitly?
                        •     Ambiguities at function block level
                        •     Typically in smaller projects



Georg Neugschwandtner                               KNX Scientific Conference 2007, Duisburg                   Page No. 12
Automation Systems Group, TU Wien                                                                             November 07




              Resolving ambiguities

                      At device level, with central configuration manager
                        a) Enter device serial number at manager (stickers)    LT-S
                        b) Enter freely assignable device tag at manager (Code wheels, DIP
                           switches)     LT-S
                                                                                              S    LT-S
                        c) Put device into “listening mode”, manager broadcasts unique tag
                                                                                                Cntrl.
                        d) Have device send out a unique tag (serial number or assigned by
                           manager)      Cntrl.
                        e) Manager enumerates and sequentially highlights possibilities, user
                           confirms (or disapproves)     Cntrl.
                      At function level (set of endpoints), peer to peer
                                                                           LT-S   LT-R         (deprecated)
                        •     As in (b), but setting tags at both partners
                        •     As in (c) or (d) – now symmetric      PB          LTE
                        •     (a) would be cumbersome; (e) only useful with minimum UI
                                 could use manager                    A
                      Approaches have different strengths
                        •     Online/offline, device replacement, …


Georg Neugschwandtner                               KNX Scientific Conference 2007, Duisburg                   Page No. 13
Automation Systems Group, TU Wien                                                                             November 07
              Determining matches

                      Manager or individual devices need to be able to determine
                      suitable matches
                        • No ambiguity      no manual intervention should be required
                        • Only allow (or offer) potentially useful bindings
                      Discovery and self description
                        • Network and device management services
                        • Device level: Manufacturer + Application IDs
                        • Function level: Channel codes, Connection codes; Object types
                                    - Channel: set of Datapoints, Connection: single DP + channel-related semantic
                        • Flexibility vs. determining matches easily; combinatorial issues
                      Content addressing
                        • Functions and zoning information mapped to group address
                          namespace
                        • Use default zone/tag in case of single instance



Georg Neugschwandtner                                  KNX Scientific Conference 2007, Duisburg                       Page No. 14
Automation Systems Group, TU Wien                                                                                    November 07




              Everything easy? Or automatic?

                      KNX configuration modes exist in “parallel
                      universes” (more or less)
                      Different strengths
                        • e.g., TX-only device support, downward compatibility

                      Use identifier namespace differently
                      LTE-mode and A-Mode also differ in runtime
                      interworking
                        • Interface object properties, group interface objects

                      Lowest common denominator: S-Mode interface
                        • And due caution (respect reserved ranges)

Georg Neugschwandtner                                  KNX Scientific Conference 2007, Duisburg                       Page No. 15
Automation Systems Group, TU Wien                                                                                    November 07
              LonWorks ISI

                      “Interoperable Self Installation”
                        •     Freely published company standard, licensed
                        •     Introduced in 2005 (together with Powerline smart transceivers)
                        •     Support for one TP and one PL segment
                        •     < 32 devices or < 200 with domain address server
                      LON communication and interoperability
                        • Various channel types, most important TP (FT/LP), PL, EIA-852
                        • Addressing modes: Broadcast (single subnet or all subnets),
                          unicast (subnet/node or Neuron ID), multicast (group)
                        • Acknowledged unicast and multicast,
                          repeated and single unacknowledged delivery
                        • Network Variables, NV selectors
                        • LonMark interoperability: SFPTs, SNVTs, SCPTs
                        • Device identification: Service pin, Wink function


Georg Neugschwandtner                                  KNX Scientific Conference 2007, Duisburg                    Page No. 16
Automation Systems Group, TU Wien                                                                                 November 07




              LonWorks ISI

                                              Invitation (user initiated or periodically)


                                    Provisional approvement (if user intervention required)


                                                              Acceptance



                      Local user interaction or via connection controller (discovery)
                      Matching connections determined via profile number + variant
                        •     Connection assemblies (or single SNVT)
                        •     Partial connections possible (local responsibility)
                        •     Automatic connections announced differently
                      Fixed assignment of group address space to usage categories
                        •     Sensors, HVAC, …
                      “Fire and forget”
                        •     Lower-layer network resources (subnet/node addresses, NV selectors) are chosen at
                              random and their use announced; other devices have to “give way”
                      Unacknowledged multicast (optionally acknowledged unicast)

Georg Neugschwandtner                                  KNX Scientific Conference 2007, Duisburg                    Page No. 17
Automation Systems Group, TU Wien                                                                                 November 07
              Project specific endpoint semantics

                      Project specific endpoint identifiers (tags)
                        •     Need to be the same on both sides of the connection to establish a binding
                        •     But is this everything?
                      Consider adding a visualisation panel
                        •     Manufacturer-provided self description cannot tell me if a tag belongs to the light in
                              the lobby or the living room
                        •     Endpoints now require specific local context to be useful
                        •     Usually, this is recorded in the panel
                      Now, consider adding a gateway for remote access
                        •     Record everything over again?
                      Suggestion: Localisation database
                        •     Available for access over the network
                        •     Implementation e.g. as Interface Object, discovery via NetworkParameter_Read
                        •     Information only needs to be maintained in a single place
                        •     Easiest form: Key-value map (group addresses with Connection V attribute
                              description string), advanced: tree structure/s (location of effect, …)
                        •     Start with push-button binding, add complexity only as required



Georg Neugschwandtner                                KNX Scientific Conference 2007, Duisburg                           Page No. 18
Automation Systems Group, TU Wien                                                                                      November 07




              Outlook

                      Automatic routing
                      Protocol security
                      Resource efficiency
                        • Regarding configuration procedures as well as resulting
                          communication relationships

                      Even more important for wireless networking
                        • Mesh topology, totally open medium

                      Improvements regarding the design of the
                      distributed application model
                        • Simple yet powerful; better integration of configuration
                          modes


Georg Neugschwandtner                                KNX Scientific Conference 2007, Duisburg                           Page No. 19
Automation Systems Group, TU Wien                                                                                      November 07

								
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